Bruce Wayne/Batman: Christian Bale
The Joker: Heath Ledger
Harley Quinn: Mila Kunis
Everyone else like Jim Gordon, Alfred, etc would be the same.
What if Heath Ledger played the Joker in The Dark Knight Rises? It would still of course have the same plot of Bruce Wayne giving up being Batman for a couple of years due to the events of the previous film, and The Joker has been in Arkham for a couple years. A charismatic and mysterious gang leader named Harley Quinn, who is inspired by the Joker, and her gang begin committing random acts of violence. Gotham's street criminals have united behind Harley, and they head for Arkham, to break out the Joker so he can lead them.
As soon Harley and the Joker meet, they fall in love instantly and go on a murderous crime spree that plunges Gotham into total anarchy. Which of course leads Batman and his allies to try and stop him.